The present invention relates to improvements in so-called "power-blocks" of the type used to connect a water-cooled power cable to both an electrode of a power source and a water supply/disposal conduit.
In various electrical systems in which relatively high currents (e.g. several hundred amperes or more) are applied to a load, it is known to cool the current-carrying cable with a liquid coolant in order to, increase the cable's current-carrying capacity. Typical of such electrical systems is a TIG arc welding system in which a high current is supplied to a non-consumable (.e.g. tungsten) electrode of a welding torch through a water-cooled power cable. Such cables commonly comprise a braided wire conductor which is loosely surrounded, along its entire length, by a flexible sleeve of dielectric material (e.g. plastic or rubber) through which water (or some other liquid coolant) is caused to flow.
In water-cooled welding systems, one end of the welding torch's power cable is connected to the welding machine's power supply via a "power block", sometimes known as a "power cable adapter". The power block provides a dual function of coupling the power cable to the welding machine's power supply, and of coupling the power cable to a liquid coolant supply, or to a coolant disposal or recirculation system. For maximum cooling efficiency, the coolant is usually supplied to the power cable through a connector in the welding torch, the water being supplied directly to the torch through a separate coolant line. In this configuration, the coolant returns to the welding machine through the power cable for disposal or recirculation. Of course, the reverse configuration is possible in which the coolant is supplied through the power block of the welding machine and, upon passing through the torch, the coolant is dispensed or recirculated through a separate line.
Referring to FIGS. 1-3, a conventional power block of the type mentioned above typically comprises a rectangularly-shaped housing 10 having an upwardly extending integral flange 12. The housing and its flange are made of solid brass or some other metal of high electrical conductivity. A circular aperture 16 is formed in the integral flange so that the power block can be supported by a threaded metal post 18 which typically extends horizontally from the control panel of the welding machine, such post constituting the high voltage electrode of the machines internal power supply P. As best shown in FIG. 2, a pair of threaded cylindrical ports 20,22 are formed in the opposing ends of the power block's housing, such ports being in fluid communication with each other by a narrow passageway 24. Port 20 is often smaller in diameter than port 22 and is adapted to receive the threaded nipple 26 comprising the connector 28 of a water conduit 30. Similarly, port 22 is adapted to receive the threaded nipple 32 comprising the connector 34 of a water-cooled power cable 36 which, as shown, is usually somewhat thicker than the water conduit 30. As noted above, power cable 36 may comprise a heavy-duty braided wire conductor 38 which is loosely surrounded by a flexible plastic sleeve 40 so that a liquid coolant (usually water) can flow along the length of the conductor. Thus, as indicated by the arrows in FIG. 1, the water coolant flows on a straight line directly through the power block. Power blocks of the type shown in FIGS. 1-3 are disclosed, for example, in U.S. Pat. No. 4,942,281, issued to C.F Srba.
In using power blocks of the above type, it will be seen from FIG. 2 that the water conduit 30 and power cable 36 extend horizontally outwardly., in opposite directions, from the respective ends of the power block. Owing to the respective weights of the water conduit and cable, there is tendency for creases C to form in the flexible water-containing sleeves of these elements, usually in the vicinity where the sleeve looses contact with a sleeve-supporting tubular fitting 41, 42, comprising the connectors 28 and 34, respectively. Through continued movement of the conduit and cable, as occurs during the welding operation, such creases can eventually give rise to coolant leaks, requiring repair or replacement of the coolant conduit and power cable.
While some welding machines are especially adapted for TIG and MIG welding, such systems are sometimes operated in a so-called "stick" welding mode to supply current to a consumable "stick" electrode. To operate in a stick welding mode, it is necessary to connect the welding machine's power post 18 (FIG. 3) to a relatively heavy-duty (uncooled) power cable. The latter is used to couple electrical energy between the welding machine's power supply and a stick electrode holder. Rather than removing the power block and connecting the stick power cable directly to the power post, the welder will more often simply loosen the nut N that holds the power block in place on the power post 18 and connect the stick electrode power cable to the post through a standard U-shaped cable lug. The nut is then retightened to hold both the power block and stick electrode cable lug in place. Thus, the power source can now be used for different types of welding operations, depending on which power cable is used and the power source settings. But there are at least two problems with this type of arrangement. First, when a conventional power block is supported by the machines power post, there is usually no room to accommodate the additional stick welding cable. It is not only difficult to make a good electrical connection between the stick power cable and the power block, but also the stick power cable will be directed upwardly, usually at some inconvenient angle, which enables slight movements of the stick power cable to loosen the retaining nut and thereby disrupt power to the stick electrode. Secondly, whenever both the water-cooled and stick power cables are connected to the power source, the available power supplied to the TIG/MIG torch is compromised. Often, rather than disconnecting the stick power cable prior a TIG welding operation, a welder will simply coil-up the stick power cable and hang it somewhere on the machine. This can be problematic because, should the welding machine be operated in an AC mode (e.g. for non-ferrous metal welding), the coiled stick cable can have the effect of decreasing the available amperage to the torch, as well as reducing the high-frequency component required to establish a welding arc without physically touching the tungsten electrode to the workpiece.